Rotary grinding wheel

ABSTRACT

A rotary abrasive grinding head adapted progressively to traverse a pre-grooved refractory surface, embodying impact members which fracture the intervening ribs between the grooves and thus remove the fractured fragments, and also embodying abrasive members which eradicate the residual or remaining portions of the ribs.

Unite States Patent Metzger et al.

[ ROTARY GING WHEEL [72] Inventors: Leopold H. Metzger, Highland Park;

Harold C. Miller, Chicago, both of Ill.

Super-Cut, Inc., Chicago, Ill.

Apr. 13, 1970 [73] Assignee:

[22] Filed:

[21 Appl. No.: 27,565

Related U.S. Application Data [62] Division of Ser. No. 731,591, May 23,1968, Pat. No.

[45] May 23, 1972 5 6] References Cited UNITED STATES PATENTS 2,980,0984/ 1961 Wayland ..51/209 X 135,642 2/1873 Grear ..125/3 PrimaryExaminer0thell M. Simpson Att0rney-N0rman H. Gerlach [57] ABSTRACT Arotary abrasive grinding head adapted progressively to traverse apre-grooved refractory surface, embodying impact members which fracturethe intervening ribs between the grooves and thus remove the fracturedfragments, and also embodying abrasive members which eradicate theresidual or remaining portions of the ribs.

3 Claims, 5 Drawing Figures Patented May 23, 1972 3,664,068

INVENTORS LEOPOLD H METZ JER HARULD Q MILLER W Afly ROTARY GRINDINGWHEEL The present application is a division of copending United Statespatent application Ser. No. 731,591, filed by Leopold H. Metzger andHarold C. Miller on May 23, 1968 and entitled METHOD OF AND APPARATUSFOR SURFACING REFRACTORY SLABS AND THE LIKE, (now U.S. Pat. No.3,550,575, granted on Dec. 29, 1970).

The present invention relates to a novel rotary grinding head which isparticularly useful in connection with the surfacing of a refractory orsimilar surface which has been pregrooved in order to provide amultiplicity of closely spaced, parallel intervening ribs between thegrooves, such head being operative in connection with use thereof andwhile traversing the surface in a longitudinal direction to fracture theribs progressively and at the same time to eradicate the residual orremaining portions of the ribs. The invention is not necessarily limitedto such use and a rotary grinding head embodying the principles of thepresent invention may, if desired, and with or without modification asrequired, be employed for treating other irregular surfaces, such, forexample, as concrete pavement or the like having abrupt high spots orother areas which are capable of being fractured by impact.Irrespective, however, of the particular use to which the improvedrotary grinding head may be put, the essential features thereof are atall times preserved.

It is obvious that in surfacing a concrete, marble, granite or similarrefractory block or slab for the purpose of reducing the faces thereofto a flat or planar condition, it is necessary by way of grinding tosurface the slab on each face thereof to a depth which is no less thanthe depth of the lowest point thereon. This means that all of therefractory material which lies outside of the plane of such lowest pointmust be removed. Where grinding operations are resorted to by utilizinga cylindrical or a planar abrasive grinding wheel or head, for each unitvolume of material that is removed from the slab, a proportional unitvolume of abrasive material on the grinding head is consumed.Considering a slab having a high region of large base area on a facethereof, the amount of refractory material which must be removed toreduce the face to a flat or planar condition is appreciable and, wherea diamond type grinding head is utilized for surfacing purposes, thecost of the diamond particles that are expended to eliminate the highregion is extremely high.

The present invention is predicated upon the use of a method like thatwhich is disclosed in aforementioned patent No. U.S. Pat. No. 3,550,575and wherein large amounts of material may be removed from a refractorysurface with a minimum amount of grinding, thus materially reducing theexpenditure of abrasive material which is employed in connection with asurfacing operation. For a full understanding of such method, referencemay be hade to such application, but for purposes of disclosure hereinit is deemed sufficient to state that the method comprises sawing amultiplicity of closely spaced, relatively deep parallel kerfs orgrooves in the surface of the block or slab underoing surfacing, thusleaving a series of intervening and spaced apart ribs which are bynecessity of appreciable height. Thereafter, the ribs are fracturedadjacent to their bases and thus broken away, leaving only a modicum ofgrinding to be performed before the surface is reduced to a flat orplanar condition. The present invention is particularly concerned with anovel rotary grinding head by means of which such fracturing andgrinding operations are carried out.

In carrying out the invention, there is provided a rotary grinding headhaving mounted thereon an annular series of impact members which are inthe form of solid tungsten carbide blocks and sweep inwardly toward theribs or other high spots undergoing fracturing from the sides thereofnear their bases. Each block-like impact member, in addition to itsimpacting or hammering function, serves as a protective front for anabrasive grinding segment which lies directly behind or trails it and isdisposed at an effective level slightly higher than the effective levelof additional abrasive segments which perform the final cleaning up orfinishing operation.

In the accompanying single sheet of drawings forming a part of thisspecification, there is illustrated an exemplary form of grinding headwhich is capable of performing the aforementioned impacting and grindingfunctions.

In this drawing:

FIG. 1 is a side elevational view of a grinding head embodying thepresent invention, such head being in operation on a grooved surface;

FIG. 2 is a bottom plan view of the grinding head proper;

FIG. 3 is an enlarged fragmentary side elevational view of the grindinghead;

FIG. 4 is an enlarged vertical sectional view taken on the line 44 ofFIG. 2; and

FIG. 5 is a horizontal sectional view taken on the line 5-5 of FIG. 1.

Referring now to the drawings in detail, and in particular to FIG. 1,the improved grinding head of the present invention is designated in itsentirety by the reference numeral 10 and is shown as being provided withan upstanding drive shaft 12. The latter has fixedly mounted thereon apulley 14 which is driven by an endless belt 16, the drive shaft beingrotatably journalled in a bearing member 18, which is associated withthe framework 20 of the grinding machine (not shown) with which the head10 is associated. The grinding wheel is shown in FIG. 1 as beingoperatively applied to the upper surface of a grooved slab, a section ofa strip of concrete pavement or other workpiece W upon which the head isadapted to operate.

The grinding head 10 is comprised of a cylindrical body 30 having alower annular end face 32 which is defined by a central recess 34. Thelower peripheral edge 36 of the body 30 is bevelled in order to providea frusto-conical area. Two annular series of abrasive segments 38 arefixedly mounted on the lower annular end face 32 of the body 30, suchseries being arranged concentrically and spaced a comparatively smalldistance apart in a radial direction. The segments 38 are spaced apartin a circumferential direction. An annular series of similarly spacedapart abrasive segments 40 is fixedly mounted on the bevelled edge 36.Another annular series of similarly spaced apart abrasive segments 42 isfixedly mounted on the outer cylindrical side surface 44 of the body 30.The various segments 38, 40 and 42 are of elongated rectangular design,the segments of each series being disposed in end-toend but spaced apartrelationship. Each of these segments is formed of sintered metalthroughout which there are uniformly distributed quantities of crushedor fragmented diamonds.

As best illustrated in FIG. 3, each of the abrasive segments 42 ispreceded by an impact member 46 in the form of an elongated rectangularblock of tungsten carbide or other hard material having a highresistance to shattering upon impact. The various blocks 46 extendvertically in parallel side-by-side but spaced apart relationship andthe lower region of the trailing side of each block 46 bears against theleading end face of the associated trailing abrasive segment 42 asclearly shown in FIG. 3. The medial and upper regions of each block-likeimpact member 46 project above the upper face of its associated abrasivesegment 42.

In the operation of the rotary grinding head 30, the function of theblock-like impact members 46 and their trailing abrasive segments 42 isto cut arcuate swaths through the oncoming high spots in the workpiece Wundergoing surfacing. In the illustrated environment for the grindinghead 30, the workpiece W is considered to be a refractory slab which hasbeen pre-grooved as shown in FIGS. 1 and 5, the grooves 50 establishingintervening ribs 52 therebetween. It will be understood, of course, thatduring the surfacing operation there will be a relative traversingmovement between the workpiece W and the head 10. In the case of a slabsurfacing machine such as is disclosed in aforementioned U.S. Pat. No.3,550,5 75, means are provided for causing the slab to traverse thesurfacing head, but in the case of a pavement surfacing machine, thehead 10 will ordinarily be carried on a vehicular type of framework sothat forward movement of the framework will cause the head to traversethe pavement.

Considering each tungsten carbide impact member 46 and its associatedabrasive segment 42 as a unit, the function of the annular series ofunits on the outer cylindrical surface 44 of the cylindrical body 30 ispartially a chipping operation and partially an abrasive operation,large segments of the ribs 52 being variously fractured and broken fromthe ribs and thus forcibly ejected from the vicinity of the working areaof the head by the impact force of the tungsten carbide, block-likemembers 46. The abrasive segments 42 which trail the impact membersinitiate a preliminary grinding operation on the portions of the ribs 52which are not dislodged by said members, while further progressivegrinding operations are performed by the abrasive segments 40 on thebevelled edge 36 of the cylindrical body 30 of the head 10. This isfollowed by a smoothing operation under the influence of the abrasivesegments 38 on the lower annular end face 32 of the body 30.

The segments 42 are largely abrasive in their function, but they alsohave a minor impact function of appreciably less proportions than theimpact function of the tungsten carbide impact members 40. This minorimpact function of the abrasive segments 42 is related to the removal byimpact of any small protuberances which may remain on the fracturedportions of the ribs 52 after the tungsten carbide impact members 46have passed thereover.

The function of the abrasive segments 38 is entirely abrasive, thesesegments serving to bring to a planar condition, as indicated at 56 inFIGS. 1 and 5, any trace of rib structure which may remain after the ribregions of the workpiece W have been traversed by the grinding head 10.

It is to be noted that there is a vertical overlap between the abrasivesegments 42 and 40, as well as between the abrasive segments 40 and 38in order that continuity of removal of the material of the ribs will beassured.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit or scope of the invention.

Having thus described the invention what we claim as new desire tosecure by letters patent is:

l. A rotary abrasive grinding head adapted progressively to traverse apre-grooved refractory surface in a longitudinal direction with respectto a series of ribs established between the grooves and thereby toremove such ribs and reduce the refractory surface to a planarcondition, said grinding head comprising a generally cylindrical bodyhaving a circular end face said end face being bevelled to provide afrusto-conical area, a cylindrical side surface, a series ofcircumferentially spaced impact members mounted on said side surface andadapted to traverse said ribs crosswise during the forward progressivemovement of the head and by impact therewith fracture the same and ejectthe fragments produced by the fracture, an abrasive segment mounted onsaid side surface and positioned immediately behind each impact member,each of said abrasive segments having a forward abrasive surface whichis substantially coplanar with the forward surface of its associatedimpact member, an annular series of abrasive segments concentricallymounted on said end face and adapted during such forward progressivemovement of the head to eradicate the residual portions of said ribs anda second annular series of abrasive segments on said frustoconical area.

2. A rotary abrasive grinding head as set forth in claim 1 and whereinthe extent of said impact members in the axial direction of the head isoverlapped by the extent of said second annular series of abrasivesegments, and the extent of said latter series of abrasive segments isoverlapped by the extent of said row of abrasive segments on said endface.

3. A rotary abrasive grinding head as set forth in claim 1 and whereinall of said abrasive segments are in the form of elongated block-likematrices containing fragmented diamonds and the axes of elongation ofwhich extend generally in a circumferential direction.

1. A rotary abrasive grinding head adapted progressively to traverse apre-grooved refractory surface in a longitudinal direction with respectto a series of ribs established between the grooves and thereby toremove such ribs and reduce the refractory surface to a planarcondition, said grinding head comprising a generally cylindrical bodyhaving a circular end face , said end face being bevelled to provide afrusto-conical area, a cylindrical side surface, a series ofcircumferentially spaced impact members mounted on said side surface andadapted to traverse said ribs crosswise during the forward progressivemovement of the head and by impact therewith fracture the same and ejectthe fragments produced by the fracture, an abrasive segment mounted onsaid side surface and positioned immediately behind each impact member,each of said abrasive segments having a forward abrasive surface whichis substantially coplanar with the forward surface of its associatedimpact member, an annular series of abrasive segments concentricallymounted on said end face and adapted during such forward progressivemovement of the head to eradicate the residual portions of said ribs ,and a second annular series of abrasive segments on said frusto-conicalarea.
 2. A rotary abrasive grinding head as set forth in claim 1 andwherein the extent of said impact members in the axial direction of thehead is overlapped by the extent of said second annular series ofabrasive segments, and the extent of said latter series of abrasivesegments is overlapped by the extent of said row of abrasive segments onsaid end face.
 3. A rotary abrasive grinding head as set forth in claim1 and wherein all of said abrasive segments are in the form of elongatedblock-like matrices containing fragmented diamonds and the axes ofelongation of which extend generally in a circumferential direction.